For all the (generally reasonable) advice to avoid linear-depth recursion in production code, I see little evidence that programmers at large know how to transform non-trivial recursive code into non-recursive stack-based code in a systematic way.
Aside from security/robustness concerns, it's also useful to transform push-based ("visitor") code to pull-based ("iterator") code. Even in languages with generators or coroutines, their overhead might be prohibitive.
And even though concerns about the cost of function calls are a bit old fashioned, if you have a piece of recursive code that's simple enough, you can sometimes get serious performance gains. There's an old example here: gist.github.com/pervognsen/a19…
Here's the generated machine code: gist.github.com/pervognsen/ce1…. It keeps almost everything in registers. The only memory traffic are to the explicit stack and the input string.
(I wouldn't necessarily recommend this particular approach since it's a little "out there", but you can do the moral equivalent of it in a more bare-handed way.)
